Here's a place where I can post my thoughts on new papers, provide updates on my projects, and post info that will eventually be on my website The Theropod Database - http://theropoddatabase.com/ . It will center on theropods, but may delve into other topics as well such as phylogenetics.

Wednesday, March 2, 2011

The Ornithischians- Zhao's nomina nuda part 8

Well, that was a sad month post-wise. But the good news is that I got my part of the manuscript finished, so now we'll see how the submission goes. Here's a post to finish the Zhao series, dealing with his ornithischians. No illustrations are known for the undescribed taxa, and the relationships and post-description data aren't discussed for the four officially described genera. Sorry about the small text size below and oddly different formatting for Monkonosaurus- Blogger's terrible when it comes to pasting things from Word. The text looks large and identical in the compose window...

Coming up, the rest of the "suggested phylogenetic definitions" series and a (perhaps not so-)surprise announcement of a new section for the Database I've been working on.

"Tianchungosaurus" Zhao, 1983Etymology- May have the same etymology as Dianchungosaurus, which refers to the Dianzhong Basin of Yunnan. Alternatively, Tianzhong would mean "in the fields", but the etymology remains uncertain since the name was not also written in Chinese by Zhao.Early Jurassic
China
Comments- Stated to be a pachycephalosaur, but Zhao includes heterodontosaurids and ceratopsians in this group too. He referred it to his new superfamily Tianchungosauroidea, supposedly ancestral to other marginocephalians and including Heterodontosaurus (which would make the superfamily Heterodontosauroidea instead). Lambert (1990) believed it may be a misspelling of Dianchungosaurus (then thought to be a heterodontosaurid, since identified as a mesoeucrocodylian), which was also followed by Olshevsky (1991) and The Paleobiology Database.

Dianchungosaurus? "elegans" Zhao, 1985Etymology- The species name means elegant.Hettangian, Early Jurassic
Zhangjiawa Member of the Lufeng Formation, Dianchung, Yunnan, China
Comments- Zhao (1985) stated this was a heterodontosaur, and that chaoyangsaurids evolved from it. Chure and McIntosh (1989) place this in Pachycephalosauridae and mark this name as sic, perhaps indicating they believe it to be intended as "Tianchungosaurus". Similarly, Olshevsky (1991) notes it may be the intended type species of that genus.

I've kept the above entries separate to better reflect what is known and has been said about each name. It seems probable "Tianchungosaurus" and Dianchungosaurus? "elegans" refer to the same material, since the other new Jurassic taxa listed by Zhao (1983) are also mentioned in his 1985 paper, both are heterodontosaurs from the Early Jurassic of China, and D and T are similar sounds. It also seems probable "Tianchungosaurus" is the misspelling, since Zhao did name additional species of other previously named genera (e.g. Megalosaurus, Plesiosaurus, Ichthyosaurus) and two heterodontosaurs having such similar names is unlikely. What's more uncertain is if "elegans" is actually a heterodontosaurid or is a crocodylian like the type species of Dianchungosaurus is now known to be. Perhaps it is best placed in Archosauria incertae sedis for now.

"Changdusaurus" Zhang et al., 1982"Changtusaurus" Zhao, 1983"Changdusaurus laminaplacodus" Zhao, 1985"Chendusaurus" Lambert, 1990"Chengdusaurus" Lambert, 1990"Changtusaurus laminaplacodus" Chure and McIntosh, 1989"Changduosaurus laminaplacodus" Fang, Zhang, Lu, Han, Zhao and Li, 2006Etymology- Changdu is a variant of Qamdo, the county the remains were found in. The species name refers to thin plates, presumably the dermal plates typical of stegosaurs. Middle Jurassic
Middle Dapuka Group, Dabuka, Qamdo County, Tibet, China
Material- (~7 m) specimen seemingly including dermal plates, and probably ischia and femoraComments- This was first announced by Zhang et al. (1982), who also gave its length. Zhao (1985) states that "transitional characters, as exemplified by the Middle Jurassic stegosaurs in Tibet" include flat ischia, a reduced fourth trochanter, and broad, thin dermal plates. These may thus be characteristics of "Changdusaurus". Lambert (1990) listed both "Chendusaurus" and "Chengdusaurus" as "perhaps Changdusaurus", but the original source of these variants is unknown. Glut (1997) incorrectly listed it as being Late Jurassic in age. Weishampel et al. (2004) list it as "undescribed ?stegosaur". Fang et al. (2006) indicated it derives from lower in the Dapuka Group than the other reported taxa. Based on the sequence of spellings, "Changdusaurus" is probably the intended one.Relationships- Stated by Zhao (1983) to be an intermediate stegosauroid, it has been assigned to Stegosauridae by later authors (e.g. Chure and McIntosh, 1989; Olshevsky, 1991). Thin plates are only known in the Loricatosaurus+Stegosaurus clade, so may indicate "Changdusaurus" is a member. All stegosaurs have reduced fourth trochanters, though those of stegosaurids are absent. Ischial thickness is not currently used in stegosaur phylogenetics. References- Zhang et al., 1982. The Roof of the World: Exploring the Mysteries of the Qinghai-Tibet Plateau. Harry N. Abrams Inc, New York. 227 pp.

Monkonosaurus lawulacus Zhao vide Dong, 1990
= "Monkonosaurus" Zhao, 1983
= "Monkonosaurus lawulacus" Zhao, 1986
= "Monkonosaurus lawulocus" Dong, 1987
= "Monkosaurus lawulacus" Chure and McIntosh, 1989Etymology- Monko is a variant of Markam, the county it was discovered in. Lawulashan is the mountain the material was discovered on.Early Cretaceous
Lura Formation, Laoran, Markam County, Tibet, China
Holotype- (IVPP coll.) (~5 m) two partial vertebrae (lost), sacrum (~311 mm), ilia (~905 mm), three dermal plates (lost)Comments- The holotype was discovered in 1976 by a team from the Chinese Academy of Sciences, and originally referred to Zhao's (1983) new thyreophoran ("armatosaurian") superfamily Oligosacralosauroidea, distinguished by its lower number of sacrals than ankylosaurids (3-5, and indeed Monkonosaurus has 5). The superfamily is invalid as there is no genus "Oligosacralosaurus", and Monkonosaurus has since been universally referred to Stegosauridae. The taxon was eventually officially described by Dong (1990), and the iliosacral block has been photographed by Dong (1987) and Dong (1990). Note Dong (1990) is incorrect that Zhao used a species name for the taxon in 1983. Maidment and Wei (2006) redescribed the material and refigured the now broken iliosacral block, believing the taxon to be indeterminate, a conclusion Maidment repeated in 2010. Glut (1997) incorrectly credits the official name to Zhao, 1983/6.References- Zhao, 1986. [unknown title] in Hao, Su, Yu and Li (eds.). The Cretaceous System of China. Stratigraphy of China. 12, 67-73.
Dong, 1987. Dinosaurs from China. Beijing: China Ocean Press. 114 pp.
Dong, 1990. Stegosaurs of Asia. in Carpenter and Currie (eds.). Dinosaur Systematics. Cambridge: Cambridge University Press. 255-268.
Maidment and Wei, 2006. A review of the Late Jurassic stegosaurs (Dinosauria, Stegosauria) from the People’s Republic of China. Geological Magazine. 143(5), 621-634.
Maidment, 2010. Stegosauria: A historical review of the body fossil record and phylogenetic relationships. Swiss Journal of Geosciences. 103, 199-210.

Polysacralosauroidea Zhao, 1983Comments- Zhao's name for Ankylosauria. Note it is invalid due the absence of a genus "Polysacralosaurus".